Gut bacteria give signals to brain cells to fight inflammation.
There is a strong assumption that the function of astrocytes is to provide nutrients and support the nerve cells of the brain. Previously, it was thought that astrocytes can also actively contribute to neurodegeneration, inflammation, and neurological diseases.
Materials and methods of research
They used advanced gene and protein analysis tools to identify a new subset of astrocytes.
Results
A new study has found that a specific subpopulation of astrocytes performs a protective, anti-inflammatory function in the brain, based on signals regulated by gut bacteria. The astrocyte population is located close to the meninges and expresses the protein LAMP1, as well as the protein TRAIL, which can induce the death of other cells. These features help astrocytes use LAMP1 + TRAIL to limit CNS inflammation by inducing cell death in inflammatory-promoting T cells.
To determine which mechanism controls astrocytes in the brain, a series of tests were performed using the gene editing tool CRISPR-Cas9. A special signaling molecule called interferon-gamma was found to regulate the expression of TRAIL. In addition, it was found that the gut microbiome induces the expression of interferon-gamma in cells that circulate through the body and eventually reach the meninges, where they can contribute to the anti-inflammatory activity of astrocytes.
Understanding the mechanisms that control the anti-inflammatory functions of astrocytes with the expression of LAMP1+TRAIL will allow the development of therapeutic methods to combat neurological diseases such as multiple sclerosis.